Phoenix Presence adapter for Jido.Messaging participant activity signals.

jido_messaging does not own realtime transport state, but Phoenix Presence is the canonical way Phoenix applications track connected users. This adapter keeps the reusable mechanics in one place:

• session heartbeats and TTL pruning
• Phoenix Presence track/update/untrack calls
• normalized jido.messaging.* participant signals

Applications still own product policy and read models. A small app module can wrap the adapter with:

defmodule MyApp.Presence do
  use Jido.Messaging.Presence,
    messaging: MyApp.Messaging,
    presence: MyAppWeb.Presence,
    topic: "my_app:presence",
    source: "my_app.presence"
end